The present invention relates generally to trailer braking systems and, more particularly, to an apparatus for actuating a trailer brake when a trailer, mounted to a pulling vehicle, becomes detached from the pulling vehicle as the trailer is being pulled.
Trailer break-away brake actuating mechanisms are known in the art. These mechanisms generally operate through a cable or chain, which is attached to a pulling vehicle by means of an S-hook or similar attachment device. The opposite end of the cable is operably connected to the trailer's braking system so that the trailer brake is actuated when the cable is pulled. When the trailer becomes detached from the pulling vehicle during operation, the trailer, no longer being pulled, tends to separate from the pulling vehicle if the safety chains fail. The S-hook, however, remains attached to the pulling vehicle. As the pulling vehicle pulls the cable, the cable actuates the trailer brake mechanism thereby stopping the trailer. The force on the cable increases until the S-hook straightens and releases the cable from the pulling vehicle. To maintain pressure on the cable and to prevent the cable from releasing the trailer braking mechanism, a friction lock is generally used to prevent the cable from retracting and prematurely releasing the trailer brake. Although such mechanisms are generally adequate to stop a break-away trailer, they do possess several inherent drawbacks.
Most prior art systems operate by means of such a friction lock to prevent the extended cable from retracting after the cable releases from the pulling vehicle. During connection and deconnection of the trailer to the pulling vehicle, the cable is often inadvertently pulled toward the pulling vehicle. Even a slight tug is often enough to actuate the break-away mechanism slightly, or to cause dangerous slack in the cable when the friction lock prevents the cable from returning taut after connection to the pulling vehicle. Even though the brake mechanism may be actuated only somewhat, this slight actuation can cause excessive wear on the trailer brake, an excessive burden on the pulling vehicle, a decrease in fuel economy, and an increase in maintenance costs. Over time, this excessive burden could even cause the trailer brakes to fail in an emergency situation. If the brake was applied over a length of time, premature lining wear or overheating could decrease the effectiveness of the trailer brakes to the point where they would no longer be able to stop the trailer.
Another problem with existing trailer break-away brake actuators is that the friction locks used to trap the cable after actuation of the trailer brakes are subject to slippage and inconsistent actuation, especially under inclement conditions. Although friction locks are simple in that they require no more than a piece of spring metal and a cable, if the friction lock becomes worn or if the cable becomes wet, it is possible that the friction lock would either not retain the cable at the proper orientation to adequately apply the trailer brakes, or that the position at which the cable was retained would be sufficient only to partially actuate the brakes, thereby causing the brakes to operate at less than their full effectiveness.
Still another drawback of prior art break-away systems is the inability of an operator to readily discern whether the system is in an actuated or nonactuated state. If an operator views a prior art device and assumes that the device is in the nonactuation state, both the pulling vehicle and the trailer could be damaged if the operator begins to move the pulling vehicle before releasing the braking system.
In a pending application, U.S. Pat. application Ser. No. 08/215,724, filed Mar. 22, 1994, entitled Trailer Break-away Device, many of the difficulties of the prior art have been overcome. That application discloses flanges connected to a releasable connection between a towing vehicle and a trailer brake system. The flanges are allowed to pass by a flange arrestment means in only a single direction, thereby locking the brake system in an actuation position when the towing vehicle separates from the trailer. The present invention utilizes a lever, which pivots relative to the break-away mechanism during actuation. The lever is more durable and simpler to use than the flange and flange arrestment means.
The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention.